July 1997
Surface Water Supply Index Report

Provided by the US Natural Resources Conservation Service
Bozeman, Montana

The SWSI is designed for areas that rely primarily on snowmelt runoff as the primary source of surface water. The SWSI accounts for snowpack, mountain precipitation, streamflow, reservoir contents, and soil moisture conditions. The SWSI can be used by irrigators, fisheries personnel, recreationists, and others who utilize surface waters. SWSI values are categorized as follows:

IDBasin NameValue
1Marias Above Tiber Reservoir2
1Marias Above Tiber Reservoir2
2Tobacco1.6
2Tobacco1.6
3Kootenai to Libby Dam2
3Kootenai to Libby Dam2
4Kootenai River below Libby Dam0.2
4Kootenai River below Libby Dam0.2
5Fisher River2.6
5Fisher River2.6
6Yaak River2.2
6Yaak River2.2
7North FK. Flathead River0.9
7North FK. Flathead River0.9
8Middle FK. Flathead River1.2
8Middle FK. Flathead River1.2
9South FK. Flathead River0.9
9South FK. Flathead River0.9
10Flathead at Columbia Falls1
10Flathead at Columbia Falls1
11Stillwater/Whitefish Rivers2.3
11Stillwater/Whitefish Rivers2.3
12Swan River1.1
12Swan River1.1
13Flathead River at Polson1.6
13Flathead River at Polson1.6
14Mission Valley1.7
14Mission Valley1.7
15Little Bitterroot River3.4
15Little Bitterroot River3.4
16Clark above Missoula1.6
16Clark above Missoula1.6
17Blackfoot River2
17Blackfoot River2
18Clark Fork above Missoula1.8
18Clark Fork above Missoula1.8
19Bitterroot River1.8
19Bitterroot River1.8
20Clark Fork River below Bitterroot River1.8
20Clark Fork River below Bitterroot River1.8
21Clark Fork River below Flathead River1.7
21Clark Fork River below Flathead River1.7
22Beaverhead River1
22Beaverhead River1
23Ruby River1.3
23Ruby River1.3
24Big Hole River1.4
24Big Hole River1.4
25Boulder River (Jefferson)1.8
25Boulder River (Jefferson)1.8
26Jefferson River1.2
26Jefferson River1.2
27Madison River1.1
27Madison River1.1
28Gallatin River1
28Gallatin River1
29Missouri River above Canyon Ferry1.1
29Missouri River above Canyon Ferry1.1
30Missouri River below Canyon Ferry1.1
30Missouri River below Canyon Ferry1.1
31Smith River3.2
31Smith River3.2
32Sun River1
32Sun River1
33Teton River1.2
33Teton River1.2
34Birch/Dupuyer2.2
34Birch/Dupuyer2.2
36Musselshell River3
36Musselshell River3
37Missouri River above Fort Peck2.5
37Missouri River above Fort Peck2.5
38Missouri River below Fort Peck2.2
38Missouri River below Fort Peck2.2
39Milk River1.5
39Milk River1.5
41Yellowstone River above Livingston1.4
41Yellowstone River above Livingston1.4
42Shields River1.7
42Shields River1.7
43Boulder River (Yellowstone)1.1
43Boulder River (Yellowstone)1.1
44Stillwater River1.1
44Stillwater River1.1
45Rock/Red Lodge Creeks1.8
45Rock/Red Lodge Creeks1.8
46Clarks Fork River1.4
46Clarks Fork River1.4
47Yellowstone River above Bighorn River1.3
47Yellowstone River above Bighorn River1.3
48Bighorn River below Bighorn Lake1.9
48Bighorn River below Bighorn Lake1.9
49Little Bighorn River0.8
49Little Bighorn River0.8
50Yellowstone River below Bighorn River1.7
50Yellowstone River below Bighorn River1.7
51Tongue River-0.5
51Tongue River-0.5
52Powder River1.8
52Powder River1.8
999Kootenai at Ft. Steele-1.1
999Kootenai at Ft. Steele-1.1